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Thread: A55 Resolution / ISO test

  1. #1
    the scanner-guy
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    A55 Resolution / ISO test

    Hi, I'm new in this forum, but I used to look in the medium format section without posting, probably for years...
    I recently bought the Sony A55 because I didn't have any "serius" digital camera(only some compact camera, and for the good pictures I used MF film) and I had to have one with stabilized sensor because I have a lot of old lenses and I wanted to use them for photo and video work.

    So, as I always do with all my equipment, I tested the camera with the "ISO 12233" resolution chart, with the kit lens and another lens, at various apertures, various ISOs, various focal lengths, etc..
    The chart is laser printed on 4 A3 paper sheets, and I was shooting outside with a Manfrotto 058b and 410 head: the non uniform light is set on purpose, to show the differences on grey gradient at various ISOs. Also the small portion of visible background works for the same reason.
    I used "JPG fine" capture because I want to shoot jpg with this camera, so I needed to see how's the moire effect in all the situations.
    All the shots were only adjusted in CS5 to match the light level (curves tool), and saved with quality settings at "8".

    This is the test with the kit lens, at 18mm and 55mm, each one at three different apertures, and always ISO100:
    18mm f/3.5

    18mm f/5.6

    18mm f/22

    55mm f/5.6

    55mm f/22

    55mm f/35


    now the same test but with an old strange lens: a Schneider Componon 150mm f/5.6: it's an enlarger lens and covers 4x5 format. I mounted it using macro bellows and various adapters.

    f5,6

    f11

    f22

    f45
    Last edited by the scanner-guy; 8th December 2010 at 12:40.

  2. #2
    the scanner-guy
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    Re: A55 Resolution / ISO test

    now the ISO noise test from 200 to 12800 (55mm f/6.3):

    ISO200

    ISO400

    ISO800

    ISO1600

    ISO3200

    ISO6400

    ISO12800

  3. #3
    the scanner-guy
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    Re: A55 Resolution / ISO test

    ..and last but not least, the same ISO noise test, but with the multi-shot noise reduction activated, and the results are quite impressive: this funcition is effective even at ISO100, with only a barely visible loss of resolution from the single-shot version.

    ISO100

    ISO200

    ISO400

    ISO800

    ISO1600

    ISO3200

    ISO6400

    ISO12800

    ISO25600


    I hope you find it useful.
    Last edited by the scanner-guy; 8th December 2010 at 12:42.

  4. #4
    the scanner-guy
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    Re: A55 Resolution / ISO test

    I thought someone would be interested.. nevermind.

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    Re: A55 Resolution / ISO test

    Hi scanner-guy

    I'm sure there are many people like me who are very interested - I've looked at all of the charts. But, a summary of your own impressions would help guide me, as I don't do this kind of testing.
    I have the a55 and really am eager to see how good it tests out in a more thorough way that just shooting images.

    Keith

  6. #6
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    Re: A55 Resolution / ISO test

    Quote Originally Posted by woodmancy View Post
    Hi scanner-guy

    I'm sure there are many people like me who are very interested - I've looked at all of the charts. But, a summary of your own impressions would help guide me, as I don't do this kind of testing.
    I have the a55 and really am eager to see how good it tests out in a more thorough way that just shooting images.

    Keith
    First off, welcome to the forum!

    Ditto - on Keith's comment
    You did a huge amount of work here but I would be really interested in what you found as it is hard to sort through all of the shots.

  7. #7
    Sr. Administrator Jack's Avatar
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    Re: A55 Resolution / ISO test

    Ditto 2 -- good work, but would like to hear a more detailed summary from you as a user!
    Jack
    home: www.getdpi.com

    "Perfection is not attainable. But if we chase perfection, we can catch excellence."

  8. #8
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    Re: A55 Resolution / ISO test

    +3

    As an A55 owner, I was interested in your post but wasn't sure what to do with all the "raw data" that you presented. It's obvious that you went through a great deal of work to gather it and share it with us.

    And if you can tell us how your test compares to other cameras/lenses that would be of interest as well.

  9. #9
    the scanner-guy
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    Re: A55 Resolution / ISO test

    I' don't have any other DSLR to compare directly, but the resolution of the camera is actually higher than the maximum scale on this standard chart, Dpreview's test on a much detailed chart said "The A55 makes good use of its 16 megapixel resolution and shows some detail up to approximately 3000 lp/ph which puts it in a similar ballpark as the 18MP Canon EOS 550D and a step ahead of the 12MP Nikon D90. The JPEG output is also fairly clean and free of artifacts and moiré."

    ..which is true if you see the pictures at ISO100.
    For comparison a d3s (12MP) can resolve 2100lines at ISO100 and a 60D (18MP), around 2700 lines, so it's very good.

    My test was to actually see the deterioration of the resolution when raising the ISO sensitivity:
    as I said at ISO 100 the sensor has around 3000lp/ph and my chart goes only to 2000, so you can't see any real difference until the resolution falls under that mark. At ISO 800 you can still see good definition on the 2000 mark near the center(so in the high-end 12 megapixel area), and then:
    1800 lp/ph at ISO1600
    1600lp/ph at ISO3200
    1400lp/ph at ISO6400 (you can find the same resolution at ISO100, but stopped down at f35)
    1200lp/ph at ISO12800.
    so every double of the sensitivity, the resolution decrease by 200 lines.
    Again, I don't have high ISO charts of other cameras, but I think tthe results are very good, at least for this price.

    Another test is the Multi-shot noise reduction: you can compare by yourself the pictures with and without it, and you'll see that the resolution doesn't change very much, in some cases with the MS-NR the image appears a little softer, and this is basically because even if you have a massive tripod and head like mine (manfrotto 058b, manfrotto 410), and some software inside the camera to align the shots, it's impossible to have two identical shots aimed at a 2000lp/ph mark... But the softness is barely visible, and only at lower ISOs, so where no one needs this feature.
    Anyway this feature is meant to reduce noise, and it works terrific. even at ISO100 you can see some noise disappearing from the bright areas, and comparing the shots you can find (look in the black and background areas) that the NR shots are a "stop" greater than the normal ones, so a ISO3200 NR picture is nearly identical, if not even better, to a normal ISO1600, and so on.
    Of course not all the subjects are suitable for this feature: it's good for still shots where the camera is handheld and the subject is not moving, but is not enough still to use a long exposure. Another use is when you want a tripod-shot perfectly noiseless (like having an ISO50 sensor).

    As I said, this is my real first non-compact digital camera: before this I had only MF film (rb67), some 35mm film (pentax) and a bunch of low cost compact digital cameras (and the scanner camera.. but this is another story..) so I don't have that much to compare about the features, menus, build quality (although it can be very funny to compare the build quality of a Mamiya rb67 to a plastic Sony A55 ), RAW performances, etcetera..

    Anyway I can say that I really like having an electronic viewfinder: I really like to have perfect sharp focus, and with the EVF I can enlarge the picture, and switch back to the main view with the histogram when I'm ready (so it's like using my Mamiya, but ten times faster...)and all of this while watching in the EVF. It's something that can change the way you take the pictures...
    Also I like the panorama feature, and the controls over the dynamic range.
    About the performances (noise, resolution, autofocus, speed) I'm satisfied for the price I paid(knowing it's on the same level of the other,and more expensive cameras), and the kit lens is good enough for video e standard pictures.
    Last edited by the scanner-guy; 11th December 2010 at 09:45.

  10. #10
    meilicke
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    Re: A55 Resolution / ISO test

    Thank you, very interesting to see real numbers on the resolution drop with increasing ISO.

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    Re: A55 Resolution / ISO test

    Thanks for this, Scanner-Guy, it helps me a lot

    I think this camera is a break-through, not only because of the translucent mirror but also because of the state of the art sensor.

    I've used the HDR function a lot and it works very well for me. I think I'll try the noise reduction mode next.

    Keith

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    Re: A55 Resolution / ISO test

    These look fantastically good - and thanks for all the hard work!

    Just this guy you know

  13. #13
    the scanner-guy
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    Re: A55 Resolution / ISO test

    you're welcome. however it wasn't really an hard work. the shooting session didn't take more than 15 minutes, I took more to write the message with all the links...

  14. #14
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    Re: A55 Resolution / ISO test

    Thanks for your time and effort! And the review. Welcome! I need to post here more myself.

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